1. Field of the Invention
The present invention relates to video games. More particularly, the present invention relates to a video game program for displaying a virtual three-dimensional space while causing a line of sight to change and at the same time displaying a character on a screen and causing the character to move in the three-dimensional space based on a direction input by a direction key to be operated by a player.
2. Description of the Related Art
Conventionally, in a video game such as a role playing game (hereinafter referred to as RPG), a game program displays a virtual three-dimensional space viewed along a certain line of sight on a screen and at the same time displays a player character in this three-dimensional space. Then, when the player operates a direction key that is composed of up, down, left and right key parts, the game program causes the player character to move in the three-dimensional space based on a direction input by the direction key.
That is, as shown in FIG. 5, the game program displays a virtual three-dimensional space image viewed along a virtual camera C's line of sight I on a screen and always detects an angle θ formed by the camera C's line of sight I and a direction line D that is an orientation of a player character P as well. Then, when a direction key is operated by a player or during operation, the game program corrects an input direction indicated by the operated direction key by the angle θ and regards this as a progress direction of the player character P to cause the player character P to progress in this direction.
That is, when the line of sight I is changed by a directional change of the virtual camera C, the angle θ changes following the change of the line of sight I. Thus, the direction input by the direction key K is corrected by this angle θ. It is therefore possible to automatically cause left and right directions of the direction key K and left and right directions of the three-dimensional space as well as up and down of the direction key K and direction of approaching and going away from the camera in the three-dimensional space to coincide with each other, respectively. Thus, if the right direction is input by the direction key K, the player character P moves in the right direction in the virtual three-dimensional space and, if the left direction is input by the direction key K, the player character P moves in the left direction in the virtual three-dimensional space.
However, as shown in FIG. 6, an image that is displayed on a screen in a game progress process may switch from a three-dimensional space image (a) photographed by a virtual camera A from the back of the player character P to a three-dimensional space image (b) photographed by a virtual camera B from the front of the player character P. In this case, since a direction of progress (←) of the character is a direction of going away from the camera A in the three-dimensional space image (a), the player is operating a down key part KD in the direction key K.
When the image switches to the three-dimensional space image from the camera B in this operating state, the progress direction (←) of the character turns into a direction of approaching the camera B in the three-dimensional space image. Therefore, in order cause the player character P to move in an identical direction in the three-dimensional space before and after the camera switches from A to B, the player has to stop operating the down key part KD at the time of switching to the image (b) and operate the up key part KU so as to cause the player character P to move in the direction approaching the camera B. As a result, smooth movement of the character becomes hard following the change of the virtual three-dimensional space image displayed on the screen, which is one reason amusement of a video game decreases.